Current sensing is important in many electrical and electronic circuits as a source control signals, including those used in automatic feedback control. However most current sensing elements, especially those based on conductive coils, are bulky or expensive to make. The two well-known current sensor devices are the current-sense transformers and the resistive shunt sensor. The former gives electrical isolation between the sensor and the active device but is generally bulky and expensive. The latter, which measures the IR drop directly from the active circuit, is compact but does not provide isolation between the sensor and the active circuit, and the power loss is high. Accordingly, there is a need for a compact, low-cost current sensor of high sensitivity that also provides electrical isolation.